A diagnostic agent is delivered intravaginally or to the interlabial space by positioning an interlabial device, such as an absorbent pad, between the labia. The pad is retained between the labia to deliver an active agent, or allow a reaction with a diagnostic agent. Alternatively, the pad is applied after the diagnostic agent is administered, to help reduce discomfort to the subject, or loss of the diagnostic agent. The active agent may be carried by the pad itself, or in an intravaginal extension of the pad, or separately in a suppository or other dosage form. In particular examples, the pad has a smaller minor portion superimposed on a larger major portion, and the smaller minor portion is inserted as a leading edge between the labia of the subject to facilitate interlabial insertion. In another example, the pad is placed interlabially after insertion of an agent.